In resolving the crisis over the customer box on which Tomcat wasn't starting, I found that the "catalina.sh" script for Tomcat needed these lines (preferably in a separate "setenv.sh" file, rather than directly in "catalina.sh"):
# Java 6 settings if needed export -s JAVA_HOME=/QOpenSys/QIBM/ProdData/JavaVM/jdk60/32bit/jre export -s CATALINA_HOME=/wintouch/tomcat export -s JAVA_OPTS="-Dos400.awt.native=true -Djava.awt.headless=true -Djava.version=1.6 -Xms256m -Xmx512m"
But it seems that the very first line of this block is overriding the JAVA_HOME environment variable I'd so laboriously set in the CL program.
Which makes me wonder . . . if I could set CATALINA_HOME and JAVA_OPTS in the CL, instead of the shell script, which would greatly simplify the installation.